Subsurface or downhole jet pumps are in increasing use in the pumping of oil wells. In more recent installations of this type, well tubing is installed in a well bore, usually with a production packer, and the jet pump assembly is pumped down the tubing into place, utilized to pump oil produced by the well formation, and later retrieved by reverse circulation to pump the jet pump assembly back to the earth's surface. The principle need in pump installations of this kind is to increase pump efficiency and thereby to pump a maximum amount of oil from a well with a designated amount of hydraulic power generated at the earth's surface.
Presently known prior art showing jet pump installations and jet pumps of this kind are disclosed in U.S. Pat. Nos. 2,080,623; 2,08O,624; 2,114,905; 4,183,722; 4,293,283; and 4,518,036. Another jet pump installation of this kind is shown on pages 5767-68 of the Composite Catalogue of Oil Field Equipment and Services (1984-1985 Edition) published by World Oil, Houston, Texas.